My dog has a heart murmor and takes 2 pills a day because of it. For the past months hes had a cough that seemed to keep gettingworse so the vet prescribed him some antibiotics. He finished taking the antibiotics after a week & out of no where he wakes up and his back left leg keeps giving out and when he does walk he seems to be walking arched. What may be the reason for this and does it have anything to do with the medicines he was taking? he was also trembling while sleeping today.